Systems
I love Glorantha, next to Hârn it’s my favourite world. I loved RuneQuest. I want to like HeroQuest, I do, I really do.

I’ve even bought the rules and made an effort to start a campaign. But I just do not like the system. The system seems contrary and slewed towards super-powerful characters. Also, the system is too ‘fuzzy’ for me. I prefer definites like ‘you’ve taken a slashing wound to the forearm to fudges like ‘you’re losing the fight.’ Trotsky likes the system, good for him, but for me, I'd still be playing Glorantha if the rules had not changed
My fellow Glorantha GM (Yes I still run a RuneQuest game, about once a year) converted his campaign from RuneQuest to Pendragon rules, just about acceptable, but he then converted again, to Hero Wars. He now admits that it was a mistake. Another player (& a friend of 20 years), when rolling a new character for me, admitted he 'doesn’t like the system much.' This is someone who will play ANYTHING. This is the ONLY game in he doesn’t like.
All of my group of players voted against moving from RuneQuest to HeroQuest. Unanimous, we're only 5 middle aged blokes and not a representative sample of gamers at large, but we've all been playing for 20+ years. Really, give this one a miss.
But, Glorantha remains a magnificent game world.
Everyone has mentioned (A)D&D so I don’t need to add my voice, but is you want another really awful game you could look at Lejendary Adventures by E Gary Gygax (should that be E Jary Jyjax?). Just download the quickstart Rules (can’t remember where I found them) for one of the most badly thought out and completely unplayable systems ever. This system has three stats with different ranges and has more confusing jargon than any system I've seen other than, possibly, Danjerous Journeys.
Gameworlds
I never liked the world of Twilight 2000. Post holocaust Europe is not my ideal adventuring location anyway, but there was something distinctly unpleasant (and in my opinion inaccurate and U.S imperialistic) in this setting.
The Warhammer World. Almost, but not quite Europe. The main differences? The existence of huge renaissance cities scattered haphazardly in the midst of huge chaos & monster infested forests, the complete lack of any farmlands to support the cities. WFRP is a pretty daft system too. amazing then, that so many of the scenarios were good.
BTW the worst scenario I've ever seen was in Dragon Magazine 100. It had the 'humourous' idea of teleporting a standard DnD adventuring party to present day London. Written by an American who had done no research and published at a time when TSR had a UK office (who either did not see this or were told to shut up).
Highlights included:
The fact that the UK now uses a decimal system of coinage 10 pennies = 1 shilling, 10 shillings = £1
The amusing idea that a fantasy DnD character, when faced with a car would jump in and try to drive it, but they'd use the door on the left side, not realising that in britain the steering wheel is on the other side. (what????)
The routine arming of police officers (still, thankfully, not the case)
The local parks being filled with two types of people, Mary Poppins style nannies and Oliver Twist style stret urchins. This is without a doubt the worst scenario I've ever seen. I can usually salvage something, but not from this mess.
BTW Tomb of Horror comes a close second. 200 ways to arbitrarily kill your players. Why?
Thank you for this cathartic experience.
Neil